1. Field of the Invention
The present invention relates generally to apparatus and methods for providing percutaneous access into the interior of body cavities. More particularly, the present invention relates to the construction and use of an apparatus for introducing one or more dilating members to provide a relatively large penetration to the hollow body cavity.
The need to percutaneously penetrate a patient's skin in order to provide access into the interior of a hollow body organ arises under a variety of circumstances. For example, various catheters, cannulas, and the like, may be introduced in order to aspirate the body cavity, introduce medication into the body cavity, perform an interventional procedure within the body cavity, and the like. Numerous devices and methods have been developed in order to provide suitable penetrations for different procedures.
One common approach for providing access to the interior of a body cavity utilizes a trocar and cannula assembly. The trocar is a metal rod with a sharp tip, while the cannula is a hollow tube which receives the trocar in its axial lumen. With the trocar in place so that its sharpened tip extends forward of the cannula, the assembly can be introduced into the body cavity, typically through a small puncture hole. The trocar is then removed, and the cannula remains in place with its lumen providing access to the interior of the body cavity.
Such trocar and cannula assemblies have been used for many years and continue to be adequate for many conventional procedures. A major limitation exists, however, when it is desired to introduce a relatively large catheter or other device through the puncture hole surrounding the cannula. The initial puncture hole is typically small and must be dilated so that larger devices can be introduced. Dilation is typically accomplished by successively introducing one or more dilating rods having increasingly large diameters through the puncture hole and into the hollow organ, typically over a flexible guide wire which has been introduced through the cannula, with the cannula then being removed. Dilating rods typically have a tapered distal end in order to facilitate their introduction and a small central lumen to receive the guide wire. The use of such conventional dilating rods is generally successful when entering cavities which are relatively close to the skin and/or which are restrained from axial movement by their structure or by attachment to surrounding fascia.
The use of dilating rods is less successful with body organs which are not axially constrained, such as the gall bladder, urinary bladder, stomach, and the like, and which have a tendency to move away from and resist entry of even a highly tapered dilating rod. This problem is worsened by the tendency of the flexible guide wire to buckle or bow slightly at the point of entry and for the unconstrained distal of the guide wire to be pulled out of position within the hollow body organ. The resulting misalignment of the guide wire and the entry path formed by the guide wire can exacerbate the problem of dilating the puncture access by causing bowing and invagination of the structure wall and tearing of the body organ away from the surrounding fascia.
Various techniques and devices have been developed to at least partly overcome these problems. For example, dilators having very small incremental increases in diameter combined with very gradually tapered distal ends can reduce the incidence of fascial detachment. That approach, however, is not always successful and the need to employ longer, more tapered dilators and/or a greater number of dilators greatly increases difficulty of manipulating the dilators and/or the time necessary for performing the procedure.
An alternate approach to prevent fascial detachment of the internal body organ has been the use of multiple separate anchors or toggles which are placed peripherally about the site of the primary puncture in order to more strongly attach the body organ to its surrounding fascia. Such an approach is generally workable, but requires a separate puncture for each anchor and subsequent suturing of each anchor in place. Again, such an approach increases patient discomfort as well as the time necessary to perform the procedure.
For these reasons, it would be desirable to provide improved methods and apparatus for forming and enlarging percutaneous penetrations into hollow body organs and cavities. The apparatus and methods should minimize additional time and complexity required for performing any associated interventional procedure, and in particular should avoid the need to make secondary penetrations in order to help secure the body organ to the surrounding fascia. The methods should be suitable for introducing dilators of virtually any diameter, including very large diameters on the order of 20 French, 24 French, and larger while avoiding buckling and misalignment of the dilator guide member. Moreover, the methods and apparatus should be compatible with virtually any type of interventional procedure which requires the formation of a percutaneous penetration for access to the interior of a body cavity.
2. Description of the Background Art
U.S. Pat. No. 4,772,266, describes a dilator/sheath assembly that may be passed over an in-dwelling guide wire in order to enlarge an access hole, with entry of the sheath further enlarging the hole. U.S. Pat. No. 1,213,001, describes a trocar and cannula assembly which includes an intermediate tube to form a three-piece structure. U.S. Pat. No. 3,742,958, discloses a cannula having an axial slot to allow the cannula to be stripped from a working catheter which has been introduced through the cannula. U.S. Pat. Nos. 4,888,000; 4,865,593; 4,581,025; 3,545,443; and 1,248,492, each describe devices suitable for percutaneous penetration of a body cavity, blood vessel, or solid tissue. The disclosures of each of the U.S. Patents cited in this paragraph are hereby incorporated herein by reference. Huibregtse, Endoscopic Biliary and Pancreatic Drainage, pages 3-5, (1988) describes the use of a Fogarty balloon catheter to introduce an endoprosthesis through a bile duct stenosis. National-Standard Medical Products, Gainesville, Fla., sells a marking needle with a retractable barb for insertion near a tumor mass, as described in a product description sheet entitled "Hawkins.TM. Breast Localization Needle."
Methods which rely on the percutaneous introduction of a catheter into the gall bladder and other hollow body organs are described in copending application Ser. Nos. 07/407,839; 07/529,077; and 07/551,971, the disclosures of which are incorporated herein by reference.